Just weeks after landing in a Martian crater in 2004, it went haywire and transmitted gibberish to Earth. Engineers eventually nursed it back to health.

As if the near-death experience wasn't enough, Spirit was upstaged early on by its twin, Opportunity, which landed in a geologic gold mine and was the first to determine that the frigid, dusty planet possessed a wetter past.

Bad luck has fallen again on Spirit. As the workhorse rover marked its sixth year on the red planet yesterday, it finds itself stuck in a sand trap, perhaps forever. The six-wheel robot geologist has been in jams before, but this is the worst predicament yet.

With Martian winter arriving in several months, Spirit may not have enough power to keep going unless scientists can point the solar-powered rover toward the sun.

The latest misfortune occurred in April when Spirit, driving backward because of a lame wheel, broke through the crusty ground like a person falling through a frozen pond and became bogged in fluffy sand. Little progress has been made to free Spirit since.